lipo noob questions

[moostrodamus]

Im thinking about 2X36v 10ah ping version 3 batteries for a 72v setup, mostly because i live in a house with 3 apartments, have no shop so cant afford to start any kind of lipo fire.... and of course you can just plug them in with no fuss...

 

[liveforphysics]

imo batteries should always be configured first to the AH needed capacity for correct cell balancing then series for the desired volts i do not think it is a good idea to pair packs for increased AH capacity
i was wanting to config a pack split on either side of bike and was thinking about possible problems with slightly mis matched packs

100% Wrong.

i dont think it its a easy thing to do way to many wires
batteries should be constructed that cells are unified into the pack as a whole battery unit
i am a newbe here but i think this is an important consideration for pack life
just think what might happen if you ganged a 10 Ah pack and a 5 AH pack that had even a slightly higher voltage
the higher voltage pack would discharge at a higher rate and could easily be damaged
as it would lose its capacity sooner
and then be like a flat tire dragging the total avg voltage down

darn i want my batteries to last for years

100% Wrong again.

 

[dogman dan]

How many amps of 72v do you want moosetrodamus? I'd say 72v 10 ah of ping would be good for about 12 amps continuous. Whatever the c rate of the v3 cells is divided in half.

You could just charge lipo in the oven, even apartments have one fire resistant place in them.

 

[moostrodamus]

How many amps of 72v do you want moosetrodamus? I'd say 72v 10 ah of ping would be good for about 12 amps continuous. Whatever the c rate of the v3 cells is divided in half.

You could just charge lipo in the oven, even apartments have one fire resistant place in them.

Is that how it is calculated? If so so much for that idea want to run a 30 amp controller. About the stove, that belongs to the landlord too...I suppose if I did have a fire i could always throw a piece of burnt chicken in there as a decoy.

At this point i'm just lurking waiting to see what you will do, you know a hell of alot more than i ever will...



Moo

 

[Russell]

Moo,

Check out this thread regarding the Ping V3;

http://endless-sphere.com/forums/viewtopic.php?f=14&t=12949&start=0

-R

 

[dogman dan]

Well, it depends on whether you want the full 1000 cycles or whatever, or if the pack is considered disposable.

There seems to be some consensus developing that whatever the c rate is, halfing it is a realistic number for continuous discharge, and getting some cycles out of it, and not exceeding 80% depth of discharge for not throwing the thing way out of balance every ride. I ran my ping v2.5 in a race recently, and got it pretty out of whack discharging a continuous 1200 watts. Less than 1c..... The kind of riding, alternating full on throttle with braking was pretty hard on it. About 20 cycles later, it seems to be gradually recovering. The packs resting voltage went from 56v to 52v in one afternoons racing. Now it's back to about 53.5v. The very brief spikes that afternoon could have been as much as 40 amps. It was a 48v 15 ah pack.

A realisitic pack size for running a larger controller would be aiming for a 1c discharge rate, so 30 ah of ping for a 30-35 amp controller. So that's aobut 40 pounds of battery. But a 72v 10 ah lipo pack of 20 or 30 c cells has a huge advantage, weighing a lot less since it can afford to be only 10 ah.

 

[justadad1957]

100% wrong ?

if you conect two packs together current will flow to the pack thats at a lower voltage
without any regard to cell voltage

old but still willing to learn more

 

[wasp]

i recently pounded the snot out of my lipo's hk 5s1p 5000mah x6 run in a 15s2p config
i ran without my turnigy meter hooked up and almost paid for it
i ran wot and when i returned the cells were all around 3.2v resting exept 1 was at 2.8...
when i charged them all together it took 29ah and was still going...btw they are 15c lipo's
they have about 30 cycles on them and they recovered nicely
i post this for the newbie's to lipo, i was a hair away from thermonuclearmeltdown and a 400 dollar loss
you should never run without somekind of protection...
i will reinstall my turnigy meter and order some of gary's toys to prevent this from happening again

 

[dogman dan]

Yeah, running with no bms, lipo users need to have some kind of monitor. I'm trying to figure out how to get started cheapest so I've been looking at the 3 buck lvc alarms. One alarm on each block, or pair of paralelled blocks. Looking at the turnigy meters, I'm not sure how you use one of those at 72v, wouldn't it cook it? Do the meters just hook to the balance wires? I think the lvc alarms do so they wouldn't see 72v, just the 18v of each block. To monitor a paired block of cells, I guess I'd have to parallel the balance leads, and then attach the lvc alarm, and the balance leads would allow both cells to equalize. Hopefully not too fast as Justadad is thinking of.

Re Justadad. yes paralelled batteries will charge each other. That's one of the reasons for using a lipo cell balancer. Don't be connecting any chemistry paralell without both batteries being at the same state of charge. Series connected batteries won't charge each other, that's why you can't charge a battery with a 3.5v charger hooked to the first cell.

 

[RTLSHIP]

What's the lifespan on lipos? Though they may be excellent for model planes and racing because of high density and light weight, they don't seem too attractive for urban ebike cruising.

 

[chroot]

@dogman - screw alarm!! It really no excuse for anyone is not buying LVC boards from Geoff or Gary. Let me tell you, One of my friend distracted and killed his 24s2p cause he did not pay attention the alarm due his area pretty heavy traffic lot noise masked the alarm's buzz. His LiPo got awful bad puffed and I told him dont charge these puffed LiPo anymore. It's no good! He lost nearly $400 dollars. TOO BAD!

@RTLSHIP - LiPo usually last 500-800 cycles depends how do you treat the LiPo. If you use LVC boards protected the LiPo, charging at 4.15v, never abuse such careless dent or damage LiPo cells and It probably will outlast with little mAh loss.

If you look El-Steak's thread somewhere, His LiPo over 100 cycle, He got few of the LiPo really dying faster and he abused it lot due he was lacking of LVC protection I.E. Gary or Geoff LVC boards.

 

[RTLSHIP]

chroot, 42 mph +. I'm scared at 25-30 mph. do you use special spokes and brakes? what about suspension

 

[arnie1]

Is a a low voltage cutout board necessary if you have a Cycle Analyst programmed with low voltage setting to protect the pack? Granted the CA can't protect individual cells...

 

[chroot]

I usually cruising around 20-25mph 99% all the time. No special brakes, I am using Avid BB7 caliper and 160mm disc. My hardtail frame with 140MM travel suspension front fork. That's why I stopped doing speed on my hardtail due too much bouncing on rear tire in high speed. My next 3rd MTB ebike building will be completely treat like an Motorcycle that has full suspension in front and rear end and travel suspension will be over 6" cause I wanted more plushy suspension comfortable on rough or bad roads.

My spokes on both front and rear uses 13g pretty strong enough as long as you readjustment and tune your bike. It pretty secured so far I built new 2nd ebike. Everything runs smooth.

I commuter my ebike to work and home sometime do errands. I saved so much money on gasoline! whoo hoo

@arnie1 The controller's LVC protect just only WHOLE of battery total voltage and NO protection on each cell. Only the one solution is get LVC boards from Gary or Geoff or You homemade the LVC boards that protect each cell.

I experimented the controller LVC set to 42v (15s2p), I discovered one of LiPo went cell 1 =2.73v, cell 2 =3.29, cell 3 =3.28, cell 4 =3.25 and cell 5 =3.28 Total 15.83v. Jesus I almost killed one of LiPo which it did not had balance proper and thank god I was very paranoid that time and felt instinct double check using LiPo monitor happened saw my own eye.

NEVER AGAIN! LVC boards are a MUST have! screw LiPo monitor or alarm and controller's LVC. :lol:

chroot, 42 mph +. I'm scared at 25-30 mph. do you use special spokes and brakes? what about suspension

 

[dogman dan]

I couldn't agree more, that the lvc boards are the best way to go. But far from mandatory.

What is mandatory is having some kind of way to monitor at least the total pack voltage. Even a simple 4 buck Harbor Freight voltmeter is better than nada.

After that, the pack size buzzers are ok, if you pay more attention to the led's and mount them where you can see them. no sound indicates, A , you didn't hear it. B it got disconnected, or C maybe you have power left. A combination of total pack voltage monitoring and the buzzers is not too bad, unless you ride further than your known range without paying attention. I don't often get suprised by the beeps coming when I haven't known they were coming by either the led's blinking blue, or the CA.

Obviously a real lvc can be better. But really, even with a reliable lvc, you still want to be aware of your pack voltage so you can slow down sooner if needed, and know what your range is on that day's weather, or hills, or temperature.

 

[RTLSHIP]

deep discharge and overcharge are the main negatives issues, and an lvc functions like a BMS on the lifepo packs.
Why not both a high volt cutoff charger and hvc board to prevent overcharge? Using an alarm clock or whatever, you could get side tracked and forget.

 

[dogman dan]

Yeah why not? I'm using regular lipo chargers for mine. I don't need to charge daily, my lipo is running the bikes that are toys. So over charging is not a problem for me.

Is somebody selling a lipo lvc, ready to run? All I see at TP packs is stuff I would ruin trying to solder it up. I suppose HK is not so interested in lvc, since a lot of that stuff would be flying when it tripped.

 

[chroot]

You have choice, There is 2 choice by Gary's LVC board kit which involve lot soldering and Geoff's SMD LVC is much better no need soldering. It's "READY TO GO" LVC board.

I bought 4 Gary LVC boards and too much hassle involve lot soldering which I do not have time spare. I bought 2 of Geoff's SMD LVC board much easier for me! :lol:

 

[dogman dan]

Link to the ready to use lvc please? Is it in the for sale section? or elsewhere?

 

[spinningmagnets]

I think these are what he's refering to:

http://endless-sphere.com/forums/viewtopic.php?f=31&t=21695

 

[dogman dan]

Thanks for the link, somehow I missed that one. Lotta pages to read now.

I'm a little confused, would those 6s boards work with a 5s pack? They definitely look like just the thing to get for a 12s commuters battery. I have nothing against an LVC instead of just a warning. But if you are going to flirt with an lvc regularly, some kind of voltage indicator is nice so you know it's coming, or know it should have worked but didn't.

 

[chroot]

I know what you mean, LVC is only way stop you going kill LiPo EVEN if your LiPo is out of balancing so you will know something is wrong with your battery when it triggering "CUT OFF" via ebrake wire. I mean one of your LiPo hit 3 volt and automatically stop the current feed to the controller.

I am sure the Justin's CA should tell you how much volt left or Ah that indication tells when to run out (empty). You might want check Jeremy's design "Fuel gauage" that would indicate how much left running out energy from the LiPo battery.

Here Jeremy's Fuel Gauage viewtopic.php?f=2&t=22675

 

[dogman dan]

Yep. What makes me nervous about an LVC, is if it doesn't work, then you don't know till it's too late. But if you have an ampmeter, or even just a voltmeter, you might smell a rat if the cutoff doesn't happen. A lot of the anti bms school of thought is based on experience when an lvc didn't work for some reason. Could be as simple as the wire to the controller broke.

 

[chroot]

LVC boards do work for me and it stop me hitting below the 3 volt. I already tested on 5Ah. Somehow, I was screwed up
when i used series mode connection cause KFF destroyed the anderson connectors. ARGH

Here what I made a diagram for 20s2p requirement to use LVC boards.

 

[Kurt]

Just wanted to + my lip noob Q .


If I was to say buy 4.. 6s 5ah lipo packs to build a 44v 10ah configuration.

Assuming all the packs are balanced and fully charged to begin with. Could I then take two of the packs and simply solder the output wires together permanently in parallel and do the same with balancing plugs. Turning it into one 6s but 12 cell 10ah 22v pack. Then repeated this with the other two packs. Then took the two 10ah 22v packs and series them together to make one 10ah 44v pack for discharge on the bike.

When it came time to recharge them. I would just take them out of series and treat it as a 6s 12 cell 10ah 22v pack most likely charge them with two 6s RC lipo chargers.

I am just trying to minimise the plugs and if I can charge and balance in parallel that's great. Especial if I decided to built a bigger 20ah configuration from two sets of 4 parallel 5ah packs soldered output wires and balance plug wires permanently would make it simple

The only bad thing I can see with this is that you don't get to monitor individual cell as they are always in 2p configuration for balancing but my 20 ah headway pack is the same. I think the only way to avoid this is if they built 10ah or 20ah cells. and 5ah cells are the most economical at the moment.

Kurt